Atrazine uptake, photosynthetic inhibition, and short-term recovery for the submersed vascular plant,Potamogeton perfoliatus L.

Abstract

The processes of atrazine (2-chloro-4-[ethylamino]-6-[isopropylamino-]-s-tri-azine) uptake and release in the submersed vascular plant,Potamogeton perfoliatus L., were rapid, approaching equilibrium with the surrounding environment within one hr. The ratio of internal atrazine concentration to external concentration was approximately 10 at the point of maximum photosynthetic inhibition and rapidly increased at lower external atrazine concentrations. The I50 (the concentration inhibiting photosynthesis by 50%) for atrazine in solution was 80 μg/L with the maximum observed photosynthetic reduction (87%) at a solution concentration of 650 μg/L. Initial photosynthetic recovery ofP. perfoliatus following exposure to atrazine was rapid with oxygen evolution from treated plants (5, 25, and 100 μg/L) being statistically indistinguishable from control plants after two hr of atrazine-free wash. However, there was an indication of residual photosynthetic depression in dosed plants, even after a 77 hr recovery period. In Chesapeake Bay, potential long-term exposure of submersed plants to concentrations of atrazine greater than 10 μg/L is doubtful so that reduction ofP. perfoliatus photosynthesis under such conditions would be minimal and reversible.